July
26, 2004 — A team of NOAA scientists,
the Louisiana Universities Marine Consortium
and Louisiana State University is forecasting that the "Dead
Zone" off the coast of Louisiana and Texas this summer should
be roughly the same size as it has been since 1990. This summer's Dead
Zone is predicted to be between 4,100 and 6,500 square miles, an area
the size of Connecticut and Rhode Island combined. The average annual
hypoxia-affected area since 1990 has been approximately 5,700 square miles.
The forecast is based on nutrient loads from the Mississippi and Atchafalaya
rivers in May and June provided by the U.S. Geological Survey. (Click
NOAA image for larger view of a large zone of oxygen-depleted water in
the Gulf of Mexico, which extends across the Louisiana continental shelf
and on to the Texas coast. Please credit “NOAA.”)

NOAA funds
research cruises to track development of hypoxia. These have been conducted
monthly since January and will be completed by the end of July.

"This
effort is an example of an innovative environmental service—officially
referred to as 'ecological forecasting'—that NOAA scientists believe
will become an important tool in coming years for both decision makers
and the public," according to Richard
Spinrad, Ph.D., assistant administrator of the NOAA Ocean Service.

The Dead
Zone is an area in the Gulf of Mexico where oxygen levels are too low
to support most life. It is caused by a seasonal change where algal growth,
stimulated by input of nutrients such as nitrogen and phosphorus from
the Mississippi and Atchafalaya rivers, settles and decays in the bottom
waters. The decaying algae consume oxygen faster than it can be replenished
from the surface, leading to decreased levels of dissolved oxygen.

Research
from the team indicates that nearly tripling the nitrogen load into the
Gulf over the past 50 years has led to the heightened Gulf of Mexico hypoxia
problem. The scientists say their research will improve assessments of
hypoxic effects under various Gulf Coast oceanographic conditions. Multiple
models of the size of the hypoxic zone are useful in evaluating the influence
of nitrogen load and variations in ocean currents on the size of the Dead
Zone.

"By using river-dissolved-oxygen model based on Mississippi River
nutrient loadings in the northern Gulf of Mexico, our research team was
also able to look back more than 30 years and determine that these now
virtually perennial events were uncommon before the mid-1970s," said
Donald Scavia, professor of natural resources and environment at the University
of Michigan and former chief scientist of the NOAA Ocean Service.

Last year,
the scientific team made the first advance forecast of the annual hypoxic
event in the Gulf of Mexico. This year, scientists used two independent
models to make this forecast. Despite differences in the way the different
models function, each model predicted roughly the same size of the Dead
Zone for this year.

The modeling
effort led by Eugene Turner of LSU predicts that the Dead Zone will be
5,600 square miles and the modeling effort led by NOAA scientists predicts
the size will be 5,400 square miles (with a range of 4,100 to 6,500).

"Algal
blooms that fuel the eventual summer hypoxia events were abundant
this spring when the Mississippi River discharge peaked multiple times
with a prolonged summer peak in June through early July," said Nancy
Rabalais, chief scientist for hypoxia research at LUMCON. "The additional
input of freshwater and nutrients in the summer contributed to further
algal blooms and an intensification of stratification."

The northern
Gulf of Mexico's bottom-water summer hypoxic zone in recent years has
extended roughly 375 miles westward from the mouth of the Mississippi
River across the Louisiana/Texas border.

The NOAA
Ocean Service is dedicated to exploring, understanding, conserving
and restoring the nation's coasts and oceans. It balances environmental
protection with economic prosperity in fulfilling its mission of promoting
safe navigation, supporting coastal communities, sustaining coastal habitats
and mitigating coastal hazards.

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and research of weather and climate-related events and providing environmental
stewardship of the nationís coastal and marine resources. NOAA is part
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